Article.
Vyacheslavov L. N., Burmasov V. S., Kandaurov I. V., Kruglyakov E. P., Meshkov O. I., Sanin A. L.Spectra of developed Langmuir turbulence in a nonisothermal magnetized plasma // Physics of Plasmas. American Institute of Physics. United States. - P.2224-2230. - ISSN 1070664X. - EISSN 10897674.The CO2-laser collective scattering method was employed for measurements of and k spectra of Langmuir turbulence in a magnetized plasma with a density of the order of 1015 cm-3. The spatial and temporal scales of turbulence were determined using electron plasma frequency and by the characteristic wave number of Langmuir waves coupled directly with relativistic electrons. The k spectrum of strong developed Langmuir turbulence driven by an electron beam was determined in a broad spectral region. The spectral density of the energy of turbulence was found to surpass the thermal level by 5-11 order of magnitude. Meanwhile, the threshold of modulation instability was exceeded by an order of magnitude for perturbations transverse to a magnetic field. In addition, Langmuir waves conversion and scattering off ion-sound waves did not transfer the chief fraction of energy of turbulence.

Article.
Burmasov Vladimir S., Kandaurov Igor V., Kruglyakov Edward P., Meshkov Oleg I.Relativistic electron beam generation in a plasma-filled diode with foilless injection into a dense plasma // IEEE Transactions on Plasma Science. Institute of Electrical and Electronics Engineers. United States. - P.952-954. - ISSN 00933813.In the experiments on relativistic electron beam (REB)-plasma interaction, the foilless injection of REB from a magnetized diode is of special interest due to the low spread angle of the beam and high repetition rate of the shots. In the experiments presented, the problem of diode shortening in the presence of a dense plasma from the interaction chamber has been solved using a special drift pipe as an anode of the foilless diode. The electron beam (Ud approx. 0.7 MeV, tb approx. 100-200 ns) produced by an axially symmetric magnetically insulated diode has been injected into a magnetized hydrogen plasma column with density ranging from 1 · 1015-3 · 1016 cm-3. It has been found that the anode pipe substantially reduces the plasma flow into the diode gap, but does not stop it completely, thus the REB generation in a plasma-filled diode has taken place. In some regimes of the beam generation it becomes possible to increase significantly the injected current and total energy deposition of the beam in comparison with the case of a vacuum magnetized diode of the same geometry. The experiments have shown effective dense plasma heating under the foilless injection.

Article.
Vyacheslavov L. N., Gurko V. F., Zharov V. F., Kandaurov I. V., Kruglyakov E. P., Meshkov O. I., Sanin A. L.Study of nonlinear effects in the interaction between a REB and plasma using incoherent Thomson scattering // Plasma Physics Reports. Maik Nauka/Interperiodica Publishing. Russian Federation. - P.195-197. - ISSN 1063780X.Incoherent Thomson scattering of a powerful neodymium laser was used to study the collective effects in the interaction between a high-current relativistic electron beam and plasma. A data acquisition system with a spatial resolution of 0.3 mm, which was used for recording scattered light, made it possible to measure the parameters of superthermal tails of the plasma electron distribution function in the range up to 300 Te and small-scale fluctuations of the plasma density during the injection of a relativistic electron beam into a plasma. Avalanche photodiodes were used as detectors. The aim of the experiment is to find direct evidence of the collapse of Langmuir waves in a magnetic field.

Article.
Vyacheslavov L. N., Gurko V. F., Zharov V. F., Kandaurov I. V., Kruglyakov E. P., Meshkov O. I., Sanin A. L.Diagnostics of strong Langmuir turbulence // Plasma Physics Reports. Maik Nauka/Interperiodica Publishing. Russian Federation. - P.183-190. - ISSN 1063780X.A diagnostic system for studying strong Langmuir turbulence excited by an electron beam in a magnetized plasma is developed and used in experiments. The diagnostic method is based on laser scattering by plasma oscillations and free plasma electrons (which allows the study of the ω-and k-spectra of the oscillations and the dynamics of the space and velocity distribution functions of the plasma electrons, respectively 1. A TE CO2 laser, which allows the measurement of k-spectra in the range 0.1 ωpe/c < k⊥ < 30ωpe/c, was used as a radiation source for studying the spectra of Langmuir waves. After some modification, the CO2-laser scattering technique was used to study ω-and k-spectra of short-wavelength ion-acoustic turbulence occurring in the presence of strong Langmuir turbulence. The scattering of Nd-laser radiation (1058 nm, 40 J, and 0.3 mrad) at an angle of 8° was used for measuring the dynamics of high-energy (0.4-10 keV) tails of the electron distribution function. A 25-channel system for recording infrared radiation scattered at an angle of 90° was developed. This system is designed for measurements of microscopic characteristics of a turbulent plasma, in particular, for direct observation of plasma collapse. In addition to the laser scattering technique, a monochromator with mesh filters operating at the wavelength λ, = 470 μm was also used for studying spontaneous plasma emission at frequencies near 2ωpe. We also used two modifications of Stark spectroscopy, which is conventionally employed in such experiments, for studying turbulent microfields.

Article.
Vyacheslavov L. N., Gurko V. F., Meshkov O. I., Zharov V. F.IR Thomson scattering systems for measurement of ne, Te Profiles in open traps // Fusion Technology. American Nuclear Society. United States. - P.422-426. - ISSN 07481896.Two laser scattering systems based on Nd-glass laser and avalanche photodiodes are proposed. First system is designed for observation of radial profiles of the electron plasma density and temperature. Each of its 2-4 spectral modules consists of 25 spatial channels and includes a bandpass interference filter, low F-number camera lens, and 25-channel linear array of the avalanche photodiodes followed by amplifiers and ADCs. Every of 25 spatial channel can view the plasma volume with an adjustable length of 1.5-15 mm along the radius of a trap. In the IR spectral region the plasma background radiation is small and the main source of noise is the amplifier noise, which permits in this case observation of a plasma of a density of 1012 cm-3 with the S/N>60. The second system is intended for measuring the longitudinal ne and Te profiles and uses the LIDAR technique, which is more suitable for open traps than for large tokomaks due to considerable larger axial length. A relative simple short pulse version of the probe laser (0.51 ns, 10 J), commercially available high speed APD-preamplifier modules, and ADC, as well as very high contrast-interference filters can provide longitudinal measurements with the spatial resolution 1≤·20 cm and S/N>40for ne ≥ 1012 cm-3. The probe laser (30J, 8 ns, 1.06 μm, 0.2 mrad) and the prototype of a single spectral module for radial measurements have been developed an used in an experiment.

Article.
Burmasov Vladimir S., Kruglyakov Eduard P., Gurko Viktor F., Meshkov Oleg I., Kandaurov Igor V., Sanin Andrei L.Small-angle pulse CO2 laser scattering with a heterodyne detection for investigation of ion-acoustic waves in plasma with strong Langmuir turbulence // Fusion Technology. American Nuclear Society. United States. - P.301-304. - ISSN 07481896.A diagnostic system to measure the spatial and frequency spectra of ion-acoustic waves in plasma with strong Langmuir turbulence is being designed. High power pulsed CO2 laser system is used as primary source of radiation. A heterodyne light mixing scheme is used to detect the scattered power. Diagnostics is tested in the experiment on the interaction of high power relativistic electron beam with magnetized plasma.

ConferencePaper.
Zinin E. I., Karnaev S. E., Kiselev V. A., Meshkov O. I., Mutchnoi N. Y., Selivanov A. N., Fedotov M. G.Optical measurements of the beam parameters of the VEPP-4M storage ring // Optical diagnostics of the VEPP-4M electron-positron collider are described. The diagnostics provide the data about position and dimensions of the e-/e+ beams. The dissectors are applied for the measurements of the length and the transversal size of the bunches and for studying the collective effects. The linear CCD array provides the measurements of the vertical size of the beams. The plans of further development of diagnostics are discussed.

Article.
Blinov V. E., Bogomyagkov A. V., Gurov D. S., Karnaev S. E., Kiselev V. A., Kremyanskaya E. V., Levichev E. B., Meshkov O. I., Mishnev S. I., Naumenkov A. I., Nikitin S. A., Nikolaev I. B., Petrov V. V., Piminov P. A., Protopopov I. Ya, Simonov E. A., Skrinskii A. N., Tumaikin G. M., Shatilov D. N.Start of the experiment on the absolute calibration of particle energy in vépp-4m near the τ-lepton production threshold // Atomic Energy. Kluwer Academic Publishers. Netherlands. - P.945-949. - ISSN 10634258. - EISSN 15738205.An experiment, using the new detector Kedr, on the precise measurement of the τ-lepton mass is being readied on the VÉPP-4M. The resonance depolarization method is used for absolute calibration of the particle energy. The main difficulty in using a polarized beam at the τ-lepton production threshold (1777 MeV) is the closeness of an integral spin resonance (1763 MeV). Experiments observing the polarization of particles in VÉPP-4M after injection of the polarized beam from the VÉPP-3 storage booster with different detunings from resonance have been performed. For comparison, the depolarization time of a beam due to quantum fluctuations in the presence of characteristic disturbances of the guiding field is calculated. The temporal stability of the energy indications is studied.

ConferencePaper.
Vyacheslavov L. N., Burmasov V. S., Kandaurov I. V., Kruglyakov E. P., Meshkov O. I., Popov S. S., Sanin A. L.Strong Langmuir turbulence with and without collapse: Experimental study // Plasma Physics and Controlled Fusion. Institute of Physics Publishing. United Kingdom. - P.B279-B291. - ISSN 07413335. - EISSN 13616587.Experiments on strong Langmuir turbulence (LT) driven by electron beam are reported. The technique of cold high-current relativistic electron beam (REB) permits to set up experimental conditions that are practically important but difficult for theoretical treatment of LT. These conditions include strong kinetic effects of plasma non-Maxwellian electrons, ion-acoustic oscillations which are weakly damped due to plasma non-isothermality and dispersion of Langmuir waves that are considerably modified by external magnetic field. A relatively dense plasma permits the use of the Thomson scattering method for observation of spectra of plasma fluctuations, electron distribution function, and local dynamics of plasma density. LT is studied in two operating modes that are characterized by moderate and increased current of REB. The experimental results with moderate REB current do not support the widely accepted picture when most of the Langmuir oscillations are trapped in density cavities. The energy flow through turbulence to plasma electrons is explained without major contribution of fully developed collapse, whereas, with increased REB current dynamic density cavities of spatial scale much less than the size of turbulent region are directly observed.

ConferencePaper.
Meshkov O. I., Gurko V. F., Zhuravlev A. N., Kiselev V. A., Muchnoi N. Yu, Selivanov A. N., Smaluk V. V., Khilchenko A. D.Study of beam energy spread at the VEPP-4M // The knowledge of beam energy spread is necessary for the experimental program of the VEPP-4M collider. In this report we discuss the application of optical diagnostics for measurement of this value. The diagnostics is based on multi-anode photomultiplier and provides information about betatron and synchrotron frequencies of electron beam [1]. The beam energy spread is derived from the spectra of betatron oscillation. The results, obtained with this method, are compared with data, provided by Compton Back Scattering technique.

ConferencePaper.
Kiselev V. A., Meshkov O. I., Smaluk V. V., Zhuravlev A. N.Beam energy spread measurement at the VEPP-4M electron-positron collider // The VEPP-4M electron-positron collider is now operating with the KEDR detector for the experiment of precise measurement of tau-lepton mass. In this experiment, monitoring of beam energy spread is important to know the energy spread contribution into the total systematic error. Information about the energy spread gives an opportunity to reduce the error of the tau-lepton mass measured. The energy spread measurements using several techniques are described. Width of the J/ψ and ψ' resonances measured with the KEDR detector is used as a reference.

ConferencePaper.
Fomin E., Kovachev G., Korchuganov V., Moryakov V., Odintsov D., Stirin A., Tarasov Yu, Zabelin A., Khilchenko A., Meshkov O., Schegolev L., Zinin E., Zhuravlev A.New station for optical observation of electron beam parameters at electron storage ring siberia-2 // The given paper focuses on the project of the electron beam optical observation station which is being carried out at the synchrotron radiation storage ring SIBERIA-2 at Kurchatov Institute. The station serves for the automatic measurement of electron bunches transverse and longitudinal sizes with the use of synchrotron radiation (SR) visible spectrum in one-bunch and multi-bunch modes; the study of individual electron bunches behaviour in time with changing accelerator parameters; the precise measurement of betatron and synchrotron oscillations frequency. The station with its optical measurement system will be located outside the shielding wall of the storage ring. The paper contains an outline scheme of optical SR beam line and a block-scheme of optical measurement part, describes the principle of operation and technical characteristics of main system elements (dissector tube, CCD-matrix, etc.), and gives an estimation of accuracy of electron bunches parameters measurements.

ConferencePaper.
Meshkov O. I., Zhilich V. V., Zhuravlev A. N., Kiselev V. A., Muchnoi N. Yu, Smaluk V. V., Sinyatkin S. V.Direct comparison of the methods of beam energy spread determination in the VEPP-4M collider // The VEPP-4M electron-positron collider is now operating with the KEDR detector for the experiment of precise measurement of tau-lepton mass [1]. The nearest experimental program of the accelerator also includes a scan of the energy area below Ely J/Φ meson to search narrow resonances. The monitoring of beam energy spread is important to know the energy spread contribution into the total systematic error. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton Back-Scattering (CBS) technique [2] are compared with the value of the spread derived from the betatron motion of the beam [3] The measurements by all the methods were done at the same accelerator run, i.e. the different diagnostics can be compared directly. The value of the energy spread was determined for a set of collider operating modes, covering the energy area from 1200 MeV up to 1855 MeV.

ConferencePaper.
Meshkov O. I., Zhilich V. V., Zhuravlev A. N., Kiselev V. A., Muchnoi N. Yu, Smaluk V. V., Sinyatkin S. V.Development of the methods of beam energy spread determination in the VEPP-4M collider // The nearest experimental program of the VEPP-4M electron-positron collider and the KEDR detector includes scanning of the energy area below J/ψ meson to search for narrow resonances. The monitoring of the beam energy spread is important for these experiments. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton Back-Scattering (CBS) technique are compared with the value of the spread derived from the betatron motion of the beam and the measurements of the beam length. Similar experiments were carried out in 2006-07. They showed the necessity to improve the algorithm of energy spread derivation with CBS technique. New set of measurements was aimed at the examination of the improved algorithm.

ConferencePaper.
Kiselev V. A., Levichev E. B., Meshkov O. I., Piminov P. A., Shatilov D. N., Smaluk V. V., Zhuravlev A. N.The VEPP-4M dynamic aperture determination with beam-beam effects // To determine experimentally the particle stable area in the electron-positron collider VEPP-4M we measure the beam lifetime with high accuracy as a function of moving aperture. The measurement is performed by a photodiode installed in the collider diagnostic beam line. The experimental setup and the measurement results are described. Comparison with the tracking simulation is presented.

ConferencePaper.
Kiselev V., Levichev E., Meshkov O., Nikitin S., Piminov P.Study of beam dynamics during the crossing of resonance in the VEPP-4M storage ring // The influence of resonances on the beam dynamics in the storage rings is of a substantial interest for the accelerator physics. For example, a fast crossing of resonances occurs in the damping rings of future linear colliders during the beam damping due to the space charge tune shift that can result in a loss of particles. We have studied experimentally the crossing of resonance nearby the working point of the VEPP-4M storage ring. The observation of the beam sizes and particle losses has been done with a single-turn time resolution.

ConferencePaper.
Meshkov O. I., Zhuravlev A. N.Multi-pinhole camera for beam position and vertical angle stabilization // The VEPP-4M electron-positron collider is now operating with the KEDR detector for the experiment at the energy area between 1100 - 3000 MeV. In these experiments, monitoring of beam coordinates and angles at the interaction point is important for energy stabilization. BPM system of VEPP-4M doesn't provide the reliable information about beam orbit when machine operates as a collider. The diagnostics, described in this paper, is a good supplement for BPM data. The vertical coordinate and angle of the beam can be measured and stabilized at two points that are placed symmetrically relative to the beam interaction point. The precision of the measurements and the collider energy accessible for the diagnostics are discussed.

ConferencePaper.
Meshkov O. I., Smaluk V. V., Sukhanov D. P., Galashov E. N., Dorokhov V., Zhuravlev A. N., Kiselev V. A.Experimental comparison of performance of various fluorescent screens applied for relativistic electron/positron beam imaging // Fluorescent screens are widely used for single-pass measurements of transverse beam profile at most of accelerator facilities. Great number of materials is now used for manufacture of fluorescent screens. The linearity, sensitivity and spatial resolution of the diagnostics depend on the choice of screen substance. We made an attempt to compare a linearity and relative light yield for few types of the fluorescent materials applied for screen manufacturing. A CCD-camera and photomultiplier tube record the light flux and 2D profile of the electron/positron beam image on the screen. Experiments were carried out with the electron/positron beam energy of 350 MeV and the beam charge of 0.1 - 100 pC.

ConferencePaper.
Smaluk V., Bekhtenev E., Cherepanov V., Karpov G., Kuzminykh V., Meshkov O., Singh O. M., Pinayev I., Vetter K.Beam diagnostics for the NSLS-II booster // For successful commissioning and effective operation of the projected NSLS-II Booster, a set of beam diagnostic instruments has been designed. Fluorescent screens are used for the Booster commissioning and troubleshooting. Closed orbit is measured using electrostatic BPMs with turn-by-turn capability. The circulating current and beam lifetime are measured using a DC current transformer. The fill pattern is monitored by a fast current transformer. Visible synchrotron radiation is registered for observation of the beam image. Betatron tunes are measured using two pairs of striplines, the first pair is for beam excitation and the second one - for beam response measurement. Design and performance of the Booster beam instrumentation are described.